Basket for a multi-electrode array catheter

ABSTRACT

An electrophysiology catheter is provided. In one embodiment, the catheter includes an elongate, deformable shaft having a proximal end and a distal end and a basket electrode assembly coupled to the distal end of the shaft. The basket electrode assembly has a proximal end and a distal end and is configured to assume a compressed state and an expanded state. The electrode assembly further includes one or more tubular splines having a plurality of electrodes disposed thereon and a plurality of conductors. Each of the plurality of conductors extends through the tubular spline from a corresponding one of the plurality of electrodes to the proximal end of the basket electrode assembly. The tubular splines are configured to assume a non-planar (e.g., a twisted or helical) shape in the expanded state.

BACKGROUND

a. Field

The present disclosure relates to electrophysiology catheters. Inparticular, the instant disclosure relates to an electrophysiologycatheter that enables a more even distribution of electrodes both whenthe catheter is in contact with tissue and when the catheter is not incontact with tissue and, therefore, a more even sampling of electricalactivity in the tissue.

b. Background

Electrophysiology (EP) mapping catheters are used to generateelectrophysiology maps of tissue in a region of interest. The use of EPmapping data in the diagnosis and treatment of tissues within a body iswell known. For example, EP maps of heart tissue can be used to guideablation catheters which are used to convey an electrical stimulus to aregion of interest within the heart and create tissue necrosis. Ablationcatheters may be used to create necrosis in heart tissue to correctconditions such as atrial and ventricular arrhythmias (including, butnot limited to, ectopic atrial tachycardia, atrial fibrillation, atrialflutter and ventricular tachycardias). In addition to guiding ablationcatheters, EP maps can also be used to evaluate the effectiveness ofablation therapy, or locate ectopic sources or a critical isthmus.

An EP mapping catheter includes one or more electrodes at a distal endthat sample electrical activity in tissue. Many EP mapping cathetershaving a relatively large number, or array, of electrodes to enablesampling over a relatively wide area of interest and reduce proceduretime. Referring to FIG. 1, one type of EP mapping catheter 10 in usetoday includes a collapsible and expandable basket electrode assembly 12disposed at the distal end of the catheter 10. The basket electrodeassembly 12 assumes a compressed state as the catheter is maneuveredthrough an introducer sheath to a region of interest in the body and anexpanded state once the catheter reaches the region of interest andemerges from the sheath. The basket electrode assembly 12 includes aplurality of splines 14 on which electrodes 16 are disposed. The splines14 are coupled together at proximal and distal ends and bow outward(i.e. assume a bowed shape) when the basket assembly 12 is in anexpanded state.

The foregoing discussion is intended only to illustrate the presentfield and should not be taken as a disavowal of claim scope.

BRIEF SUMMARY

The present disclosure relates to an electrophysiology catheter. Inparticular, the instant disclosure relates to an electrophysiologycatheter that may enable a more even distribution of electrodes bothwhen the catheter is in contact with tissue and when the catheter is notin contact with tissue and, therefore, a more even sampling ofelectrical activity in the tissue.

An electrophysiology catheter in accordance with at least one embodimentof the present teachings includes an elongate, deformable shaft having aproximal end and a distal end. The catheter further includes a basketelectrode assembly coupled to the distal end of the shaft. The basketelectrode assembly comprises a proximal end and a distal end and isconfigured to assume a compressed state and an expanded state. Thebasket electrode assembly includes a spline having a plurality ofelectrodes disposed thereon. The spline is configured to assume anon-planar shape in the expanded state. The spline may, for example,assume a twisted shape and, in particular, a helical shape.

An electrophysiology catheter in accordance with at least anotherembodiment of the present teachings includes an elongate, deformableshaft having a proximal end and a distal end. The catheter furtherincludes a basket electrode assembly coupled to the distal end of theshaft. The basket electrode assembly comprises a proximal end and adistal end and is configured to assume a compressed state and anexpanded state. The basket electrode assembly includes a plurality offirst splines. Each of the plurality of first splines is configured toassume a shape other than a helical shape in the expanded state. Thebasket electrode assembly further includes a second spline. The secondspline comprises an electrode disposed thereon and is configured toassume a helical shape in the expanded state.

An electrophysiology catheter in accordance with at least anotherembodiment of the present teachings includes an elongate, deformableshaft comprising a proximal end and a distal end. The catheter furtherincludes a basket electrode assembly coupled to the distal end of theshaft. The basket electrode assembly comprises a proximal end and adistal end and a central longitudinal axis and is configured to assume acompressed state and an expanded state. The basket electrode assemblyincludes a first spline. The first spline comprises an electrodedisposed thereon and comprises a first maximum radius relative to theaxis in the expanded state. The basket electrode assembly furtherincludes a second spline. The second spline comprises an electrodedisposed thereon and comprises a second maximum radius relative to theaxis in the expanded state. The second maximum radius is different thanthe first maximum radius.

An electrophysiology catheter in accordance with one or more of thepresent teachings may enable a more even distribution of electrodes bothwhen the catheter is in contact with tissue and when the catheter is notin contact with tissue and, therefore, a more even sampling ofelectrical activity in the tissue.

The foregoing and other aspects, features, details, utilities, andadvantages of the present disclosure will be apparent from reading thefollowing description and claims, and from reviewing the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a prior art electrophysiology mappingcatheter.

FIG. 2 is a perspective view of an electrophysiology catheter inaccordance with one embodiment of the present teachings.

FIG. 3 is an enlarged perspective view of a portion of theelectrophysiology catheter of FIG. 2.

FIG. 4 is a cross-sectional drawing of the electrophysiology catheter ofFIG. 3 taken along line 4-4 in FIG. 3.

FIG. 5 is a diagrammatic view illustrating the arrangement of thesplines of the basket electrode assembly of the catheter of FIG. 3 whenthe assembly is compressed in the longitudinal direction of thecatheter.

FIG. 6 is an enlarged perspective view of a portion of anelectrophysiology catheter in accordance with another embodiment of thepresent teachings.

FIG. 7 is an enlarged perspective view of a portion of anelectrophysiology catheter in accordance with another embodiment of thepresent teachings.

FIG. 8 is an enlarged perspective view of a portion of anelectrophysiology catheter in accordance with another embodiment of thepresent teachings.

FIG. 9 is an enlarged perspective view of a portion of anelectrophysiology catheter in accordance with another embodiment of thepresent teachings.

DETAILED DESCRIPTION

Various embodiments are described herein to various apparatuses,systems, and/or methods. Numerous specific details are set forth toprovide a thorough understanding of the overall structure, function,manufacture, and use of the embodiments as described in thespecification and illustrated in the accompanying drawings. It will beunderstood by those skilled in the art, however, that the embodimentsmay be practiced without such specific details. In other instances,well-known operations, components, and elements have not been describedin detail so as not to obscure the embodiments described in thespecification. Those of ordinary skill in the art will understand thatthe embodiments described and illustrated herein are non-limitingexamples, and thus it can be appreciated that the specific structuraland functional details disclosed herein may be representative and do notnecessarily limit the scope of the embodiments, the scope of which isdefined solely by the appended claims.

Reference throughout the specification to “various embodiments,” “someembodiments,” “one embodiment,” or “an embodiment”, or the like, meansthat a particular feature, structure, or characteristic described inconnection with the embodiment is included in at least one embodiment.Thus, appearances of the phrases “in various embodiments,” “in someembodiments,” “in one embodiment,” or “in an embodiment”, or the like,in places throughout the specification are not necessarily all referringto the same embodiment. Furthermore, the particular features,structures, or characteristics may be combined in any suitable manner inone or more embodiments. Thus, the particular features, structures, orcharacteristics illustrated or described in connection with oneembodiment may be combined, in whole or in part, with the features,structures, or characteristics of one or more other embodiments withoutlimitation given that such combination is not illogical ornon-functional.

It will be appreciated that the terms “proximal” and “distal” may beused throughout the specification with reference to a clinicianmanipulating one end of an instrument used to treat a patient. The term“proximal” refers to the portion of the instrument closest to theclinician and the term “distal” refers to the portion located furthestfrom the clinician. It will be further appreciated that for concisenessand clarity, spatial terms such as “vertical,” “horizontal,” “up,” and“down” may be used herein with respect to the illustrated embodiments.However, surgical instruments may be used in many orientations andpositions, and these terms are not intended to be limiting and absolute.

Referring now to the drawings wherein like reference numerals are usedto identify identical components in the various views, FIG. 2illustrates one embodiment of an electrophysiology catheter 18 inaccordance with the present teachings. Catheter 18 is provided for usein generating an electrophysiological map of tissue and, in particular,cardiac tissue. It should be understood, however, that catheter 18 maybe used with tissues other than cardiac tissue. Catheter 18 may includea cable connector or interface 20, a handle 22, a shaft 24 having aproximal end 26 and a distal end 28, and a basket electrode assembly 30.Catheter 18 may also include other conventional components notillustrated herein such as deflection mechanisms, additional electrodesand corresponding conductors or leads.

Connector 20 provides mechanical and electrical connection(s) for cablesextending from an electronic control unit (ECU) (not shown) or similardevice that is configured to receive signals generated by basketelectrode assembly 30. Connector 20 may be conventional in the art andbe disposed at the proximal end 26 of catheter 18.

Handle 22 provides a location for the physician to hold catheter 18 andmay further provides a means for steering or guiding shaft 24 within thebody. For example, handle 22 may include means to change the length of aguide wire extending through catheter 18 to distal end 28 of shaft 24 tosteer distal end 28 and, thus, shaft 24. Handle 22 may also beconventional in the art and it will be understood that the constructionof handle 22 may vary.

Shaft 24 is an elongate, deformable member configured for movementwithin the body. Shaft 24 supports electrode assembly 30, associatedconductors, and, in some embodiments, additional electronics used forsignal processing or conditioning. Shaft 24 may also be configured topermit transport, delivery, and/or removal of fluids (includingirrigation fluids and bodily fluids), medicines, and/or surgical toolsor instruments. Shaft 24 may be made from conventional materials such aspolyurethane and defines one or more lumens configured to house and/ortransport electrical conductors, fluids, medicines, guide wires orsurgical tools or instruments. Shaft 24 may be introduced into a bloodvessel or other structure within the body through an introducer sheath.Shaft 24 may then be steered or guided through the body to a desiredlocation such as tissue in a region of interest using guide wires orpull wires or other means known in the art including remote controlguidance systems.

Referring now to FIGS. 3 and 4, electrode assembly 30 provides a meansfor conducting an electrophysiological study of tissue. Assembly 30 maybe coupled to a distal end of shaft 24 and includes a proximal end 32and a distal end 34. Assembly 30 may include a plurality of splines 36on which electrodes are disposed and that form an electrode “basket”that is configured to assume a compressed state and an expanded state.Assembly 30 may assume the expanded state in the absence of anextraneous force acting on the assembly 30 (i.e. assembly 30 may bebiased to the expanded state) or may be urged to the expanded statethrough mechanical means (e.g. wires that are pulled or pushed).Assembly 30 may assume the compressed state, for example, as catheter 18is maneuvered through an introducer sheath within the body to the regionof interest and assume the expanded state upon emerging from a distalend of the sheath. Splines 36 are configured to support electrodes in apredetermined configuration to allow contact and/or non-contact mappingof electrical activity in tissue. Referring to FIG. 4, each spline 36may include a tubular body 38, means, such as wire 40, for supportingbody 38 and biasing body 38 to assume a predetermined shape, one or moreelectrodes 42 and associated conductors 44. Although a particularembodiment for a spline, e.g., spline 36, is illustrated herein, itshould be understood that spline(s) may be constructed in a variety ofways. In one embodiment, for example, one or more splines may include aflexible circuit as described and illustrated in U.S. patent applicationSer. No. 12/958,992 (published as United States patent applicationpublication no. 2012/0143298 A1), the entire disclosure of which isincorporated herein by reference. Additional embodiments of splinesand/or basket electrode assemblies may be found described in one or moreof U.S. patent application Ser. No. 13/072,357 (published as UnitedStates patent application publication no. US 2011/0213231 A1) and U.S.patent application Ser. No. 13/340,760, the entire disclosures of whichare incorporated herein by reference.

Body 38 provides structural support for electrodes 42 and insulatesconductors 44 from bodily fluids and other elements. Referring to FIG.4, body 38 is tubular and may be annular in shape. It should beunderstood, however, that the shape of body 38 may vary. Body 38 may bemade from conventional polymeric materials such as polyurethane, andnylon or thermoplastic elastomers such as the elastomer sold under theregistered trademark “PEBAX” by Arkema, Inc. and reinforcements such asmetallic braids. Body 38 may define a central lumen 46 extending betweenproximal and distal ends 48, 50 of body 38 and configured to allowpassage of wire 40 and conductors 44. It should be understood, however,that body 38 may alternatively define one or more channels eachconfigured to receive one of wire 40 or a conductor 44. In theillustrated embodiment, wire 40 is illustrated at the center of lumen 46with conductors 44 disposed circumferentially around wire 40. It shouldbe understood, however, that the relative arrangement of wire 40 andconductors 44 within lumen 46 may vary.

Wire 40 is provided to support body 38 and bias body 38 to assume apredetermined shape. Wire may be made from a shape memory alloy such asnitinol (nickel titanium). Wire extends through lumen 46 of body 38 fromproximal end 48 of body 38 to distal end 50 and may extend through thebodies 38 of multiple splines 36 to couple one or more splines together.Alternatively, or in addition, splines 36 may be coupled at distal end50 by a hinge connector 52 or in any of the ways described andillustrated in U.S. patent application Ser. No. 13/340,760 filed Dec.30, 2011, the entire disclosure of which is incorporated herein byreference. The distal end 34 of the basket electrode assembly 30 may bespecialized to form a small, but blunt mechanical connection point sothat the distal portion of the catheter 18 may safely be pressed againsttissue.

Referring again to FIG. 3, electrodes 42 may be configured to diagnose,sense, and measure electrical activity in tissue such as cardiac tissue.One or more of electrodes 42 may also be used to provide ablationtherapy to tissue. Electrodes 42 may comprise ring electrodes disposedabout body 38 and may be made from platinum or other conductivematerials. Each electrode 42 is coupled to a corresponding conductor 44.In accordance with one aspect of the present teachings, electrodes 42may be unevenly spaced along spline 36. Referring to FIG. 5, forexample, the distance d₁ between a pair of adjacent electrodes 42 suchas electrodes 42 _(A1), 42 _(A2), on a spline 36A may be different thana distance d₂ between another pair of adjacent electrodes such aselectrodes 42 _(A2), 42 _(A3) on the same spline 36A. In accordance withone embodiment the distances between adjacent electrodes 42 on a spline36 may be smallest at or near the midpoint of the spline 36 and increasemoving towards the ends of each spline 36. This configuration allows arelatively uniform distribution of the electrodes 42 when the basketelectrode assembly 10 is fully expanded. In particular, the spacingbetween electrodes 42 on adjacent splines 36 is greater near themidpoints of the splines 36 when assembly 10 is in the expanded stateand less near the ends of the splines 36 when assembly 10 is in theexpanded state. By reducing the spacing between adjacent electrodes 42on each spline 36 near the midpoints of the spline 36 and increasing thespacing between adjacent electrodes on each spline 36 near the ends ofthe spline 36, the varied spacing between adjacent electrodes 42 on anindividual spline 36 compensates for the relative spacing betweenelectrodes 42 on adjacent splines 36 when assembly 10 is in the expandedstate. The placement of electrodes 42 along different splines 36 inassembly 30 may also differ. In particular, a distance d₃ between thedistal most electrode 42 _(A1) on a spline 36A and the distal end 50 ofspline 36A may differ from a distance d₄ between the distal mostelectrode 42 _(B1) on another spline 36B and the distal end 50 of spline36B. Similarly, the distances for corresponding electrodes 42 on splines36 from either the proximal or distal ends 48, 50 of the splines 36 mayvary (such that, for example, the distance between the proximal end 48of a spline 36 and the third electrode 42 from the proximal end 48 ofthe spline 36 differs from the distance between the proximal end 48 ofanother spline 36 and the third electrode 42 from the proximal end 48 ofthe other spline 36).

Referring again to FIG. 4, conductors 44 may be configured to transmitelectrical signals from electrodes 42 through shaft 24 of catheter 18 toan electronic control unit or similar device. Conductors 44 may comprisewires or cables or other means for conducting signals and may bedisposed with the lumen 46 of a body 38 of a given spline 36. Eachconductor 44 may be coupled at a distal end to a corresponding electrode42 and extend through lumen 46 to the proximal end 32 of basketelectrode assembly 30.

As mentioned hereinabove, the body 38 of each spline 36 may be biased toassume a predetermined shape when assembly 30 is in an expanded state.In accordance with one aspect of the present teachings, each of splines36 may be configured to assume a non-planar shape, such as a twistedshape (e.g., a helical shape), when assembly 30 is in the expandedstate. The use of a helical shape, for example, enables a more evendistribution of electrodes, and therefore more even sampling ofelectrical activity in tissue, in both contact and non-contact mapping.The use of a helical shape may also enable controlled shifting ofassembly 30 between the compressed and expanded states using, forexample, wires that may be pulled or pushed by the physician. In theillustrated embodiment, catheter 18 includes eight helical splines 36.Referring to FIG. 5, when assembly 30 is compressed in the longitudinaldirection of assembly 30 and catheter 18, assembly 30 may form aflower-shaped pattern. As a result, the electrodes 42 on splines 36 aredispersed more evenly throughout the pattern and, therefore, dispersedmore evenly throughout the area of contact with the tissue as comparedto the prior art design in FIG. 1 in which the electrodes 16 are closelyspaced near the proximal and distal ends of the splines 14, butrelatively distantly spaced near the midpoints of each spline 14 whenthe assembly 12 in FIG. 1 is compressed in the longitudinal direction.The illustrated catheter 18 may prove useful, for example, in generatinga map of a pulmonary vein which is currently done using spiral or hoopelectrode assemblies. Similarly, when assembly 30 is compressedlaterally due to the contact with tissue (e.g. perpendicular to thelongitudinal direction of the catheter), the helical shape of splines 36reduces the tendency for certain splines nearest the point of contact tomove away from one another (and towards other adjacent splines) as inthe design illustrated in FIG. 1 because a portion of each spline 36 islocated on a diametrically opposite side of the assembly 30 relative tothe point of contact. Referring again to FIG. 5, electrodes 42 may beunevenly spaced along each individual spline 36 or located at differentrelative locations along any two splines as described hereinabove tofurther facilitate a more even distribution of electrodes 42. Onemethodology for locating the electrodes 42 on multiple helical splines36 is to locate an electrode 42 on one spline 36 at a first distancefrom the end 48 or 50 of the spline 36. The next electrode 42 may belocated on a different spline--either adjacent to the first spline 36 oron a non-adjacent spline 36 with the spacing between the splinesdefining a fixed angle of rotation—at a second distance from the commonend 48 or 50 of the splines 36 different than the first distance.Subsequent electrodes 42 may be located on splines 36 by (i) rotatingthe same fixed angle of rotation relative to the spline 36 having themost recently placed electrode 42 and (ii) increasing the distance fromthe common end 48 or 50 relative to the spline 36 having the mostrecently placed electrode 42. Another methodology may involve locatingelectrodes 42 on a subset of splines 36 (e.g., every other spline 36 asshown in FIG. 5 or another combination of non-adjacent splines 36) at afirst distance from the common end 48 or 50 of splines 36 and thenlocating electrodes 42 on another subset of splines 36 at a seconddistance from the common end 48 or 50 of splines 36 different than thefirst distance and locating subsequent electrodes in a similar manner tothat described hereinabove.

Referring again to FIG. 3, in accordance with one aspect of the presentteachings, catheter 18 may further includes means, such as central post54, for rotating one end 32, 34 of basket electrode assembly 30 relativeto the other end 32, 34, of basket electrode assembly 30. Post 54 maycomprise a wire or cable in some embodiments. Post 54 may be rigidlycoupled to the distal end 50 of basket assembly 30 and may be coupled toconnector 52. Post 54 extends through shaft 24 and may be rotatablerelative to shaft 24. Handle 22 may include means, such as a rotaryactuator, through which the physician or a robotic controller may causerotation of post 54 to thereby cause rotation of distal end 34 ofassembly 30 relative to the fixed proximal end 32 of assembly 30. Inthis manner, the physician may control the helical pitch of splines 36,the mechanical stiffness of assembly 30, and the spacing of electrodes42. Post 54 may move axially relative to shaft 24 so that the length ofpost 54 will vary with the compression or expansion of basket electrodeassembly 30.

As discussed hereinabove, electrodes 42 may be unevenly spaced alongsplines 36 to achieve a more even distribution of electrodes 42 whenassembly 30 is in an expanded state. Referring to FIG. 6, however, anelectrophysiology catheter 56 in accordance with another embodiment ofthe present teachings is illustrated. Catheter 56 is substantiallysimilar to catheter 18, but the electrodes 42 on each spline 36 areevenly spaced along the spline 36 and/or placed at identical locationson each spline 36 such that one, or a limited number, of splines 36 maybe used for more efficient manufacture of catheter 56. Although catheter56 may not achieve the optimal location of electrodes 42 achieved incatheter 18, the use of helical splines 36 on catheter 56 provides animproved distribution of electrodes 42 in contact and non-contactmapping relative to prior art designs.

In the embodiment illustrated in FIG. 3, each of splines 36 has the samehelical pitch. Referring now to FIG. 7, another embodiment of anelectrophysiology catheter 58 in accordance with the present teachingsis illustrated. Catheter 58 is substantially similar to catheter 18, butincludes a different basket electrode assembly 60. As in basketelectrode assembly 30 of catheter 18, assembly 60 includes splines 62,64 configured to assume a helical shape when assembly 60 is in anexpanded state. In assembly 60, however, splines 62 have a differenthelical pitch than splines 64. As a result, splines 62 define onecircumferential or spherical envelope (indicated by the dashed line 66)when assembly 60 is in an expanded state while splines 64 define anothercircumferential or spherical envelope (indicated by the dashed line 68).Stated another way, the maximum radial distance of splines 62 from acentral longitudinal axis 70 of basket electrode assembly 60 isdifferent than a maximum radial distance of splines 64 from axis 70 whenbasket electrode assembly 60 is in an expanded state. Catheter 58 mayprovide advantages in, for example, non-contact mapping. In particular,lateral contact of assembly 60 with tissue may cause splines 64 to bendand deform from their ideal expanded state—particularly near themidpoint between the proximal and distal ends of the splines 64 whichmay comprise an important location for sampling electrical activity.Splines 62, however, may maintain their ideal expanded state andcontinue to provide sampling in the desired location. In the illustratedembodiment, splines 62, 64 rotate about axis 70 in the same direction.In an alternative embodiment, however, splines 62, 64 may rotate aboutaxis 70 in opposite directions. Rotation of splines 62, 64 (through, forexample, the use of post 54 shown in FIG. 3) would cause the pitch ofone of splines 62, 64 to increase while decreasing its maximum radialdistance from axis 70 and would cause the pitch of the other of splines62, 64 to decrease while increasing its maximum radial distance fromaxis 70. A basket electrode assembly in accordance with this embodimentwould enable a physician to change the distribution of the electrodeswith respect to the radius from the centroid of the basket.

Referring now to FIG. 8, another embodiment of an electrophysiologycatheter 72 in accordance with the present teachings is illustrated.Catheter 72 is substantially similar to catheters 18 and 58, butincludes a different basket electrode assembly 74. As in basketelectrode assembly 60 of catheter 58, assembly 74 includes two differenttypes of splines 76, 78. Splines 76 are configured to assume a helicalshape when assembly 74 is in an expanded state. Splines 78, however, areconfigured to assume a shape other than a helical shape when assembly 74is an expanded state. In particular, splines 78 may assume a bowed“longitude line” or planar shape similar to splines 14 in the embodimentof FIG. 1. Splines 76 and splines 78 again define differentcircumferential or spherical envelopes 80, 82 when assembly 74 is anexpanded state. As shown in the illustrated embodiment, the maximumradial distance of splines 76 from a central longitudinal axis 84 ofassembly 74 may be less than the maximum radial distance of splines 78from axis 84 when assembly 74 is an expanded state. In the embodimentshow in FIG. 8, splines 76, 78 both include electrodes. Referring toFIG. 9, another embodiment of an electrophysiology catheter 86 inaccordance with the present teachings may be substantially similar toelectrophysiology catheter 72, but may include a different basketelectrode assembly 88. Assembly 88 is substantially similar to assembly74, but includes splines 90. Splines 90 are substantially similar tosplines 78, but do not include electrodes.

Although several embodiments of a system in accordance with presentteachings have been described above with a certain degree ofparticularity, those skilled in the art could make numerous alterationsto the disclosed embodiments without departing from the scope of thisdisclosure. All directional references (e.g., upper, lower, upward,downward, left, right, leftward, rightward, top, bottom, above, below,vertical, horizontal, clockwise and counterclockwise) are only used foridentification purposes to aid the reader's understanding of thedisclosed embodiments, and do not create limitations, particularly as tothe position, orientation, or use of the disclosed embodiments. Joinderreferences (e.g., attached, coupled, connected, and the like) are to beconstrued broadly and may include intermediate members between aconnection of elements and relative movement between elements. As such,joinder references do not necessarily infer that two elements aredirectly connected and in fixed relation to each other. It is intendedthat all matter contained in the above description or shown in theaccompanying drawings shall be interpreted as illustrative only and notas limiting. Changes in detail or structure may be made withoutdeparting from the present teachings as defined in the appended claims.

Any patent, publication, or other disclosure material, in whole or inpart, that is said to be incorporated by reference herein isincorporated herein only to the extent that the incorporated materialsdoes not conflict with existing definitions, statements, or otherdisclosure material set forth in this disclosure. As such, and to theextent necessary, the disclosure as explicitly set forth hereinsupersedes any conflicting material incorporated herein by reference.Any material, or portion thereof, that is said to be incorporated byreference herein, but which conflicts with existing definitions,statements, or other disclosure material set forth herein will only beincorporated to the extent that no conflict arises between thatincorporated material and the existing disclosure material.

1-20. (canceled)
 21. An electrophysiology catheter, comprising: anelongate, deformable shaft comprising a proximal end and a distal end;and, a basket electrode assembly coupled to the distal end of the shaft,the basket electrode assembly comprising a proximal end and a distal endand a central longitudinal axis and configured to assume a compressedstate and an expanded state and including: a first spline comprising afirst maximum radius relative to the axis in the expanded state; and, asecond spline, the second spline comprising an electrode disposedthereon and comprising a second maximum radius relative to the axis inthe expanded state, the second maximum radius different than the firstmaximum radius, wherein the first spline and the second spline are eachcoupled to the proximal end and the distal end of the basket electrodeassembly and are each independently supported.
 22. The electrophysiologycatheter of claim 21, wherein the first maximum radius is greater thanthe second maximum radius.
 23. The electrophysiology catheter of claim21, wherein the second maximum radius is greater than the first maximumradius.
 24. The electrophysiology catheter of claim 21, wherein at leastone of the first and second splines assumes a helical shape in theexpanded state.
 25. The electrophysiology catheter of claim 21, whereinboth of the first and second splines assume a helical shape in theexpanded state and a helical pitch of the first spline differs from ahelical pitch of the second spline.
 26. The electrophysiology catheterof claim 21, wherein each of the first and second splines is tubular andincludes a plurality of electrodes disposed thereon; and, a plurality ofconductors, each of the conductors extending from a corresponding one ofthe plurality of electrodes to the proximal end of the basket electrodeassembly.
 27. The electrophysiology catheter of claim 21, wherein thefirst radius is greater than the second radius.
 28. An electrophysiologycatheter, comprising: an elongate, deformable shaft comprising an axis,a proximal end, and a distal end; and, a basket electrode assemblycoupled to the distal end of the shaft, the basket electrode assemblycomprising a proximal end and a distal end and configured to assume acompressed state and an expanded state, wherein the basket electrodeassembly further comprises a plurality of first splines and at least onesecond spline; wherein the plurality of first splines comprise a firstmaximum radius relative to the axis in the expanded state, and whereinthe at least one second spline comprises at least one electrode and asecond maximum radius relative to the axis in the expanded state, thesecond maximum radius different than the first maximum radius, whereinthe basket electrode assembly is sized and configured to fit within aheart and wherein the at least one electrode are spaced between aproximal end and a distal end of each of the at least one second splineand are configured to allow for measuring electrical activity of theheart, and wherein the plurality of splines are free floating.
 29. Theelectrophysiology catheter of claim 28, wherein the plurality of firstsplines are configured to assume a non-planar shape.
 30. Theelectrophysiology catheter of claim 29, wherein the non-planar shapecomprises a twisted shape.
 31. The electrophysiology catheter of claim30, wherein the twisted shape comprises a helical shape.
 32. Theelectrophysiology catheter of claim 28, wherein the at least oneelectrode on the at least one second spline comprises a plurality ofelectrodes.
 33. The electrophysiology catheter of claim 28, wherein thefirst maximum radius is greater than the second maximum radius.
 34. Theelectrophysiology catheter of claim 28, wherein the second maximumradius is greater than the first maximum radius.
 35. Anelectrophysiology catheter, comprising: an elongate, deformable shaftcomprising a proximal end and a distal end; and, a basket electrodeassembly coupled to the distal end of the shaft, the basket electrodeassembly comprising, a longitudinal axis, a proximal end, and a distalend and configured to assume a compressed state and an expanded stateand including: a plurality of first splines, a second spline, the secondspline comprising an electrode disposed thereon, wherein the secondspline is coupled to the proximal end and the distal end of the basketelectrode assembly, wherein a portion of each of the plurality of firstsplines is farther from the longitudinal axis of the basket assemblythan the electrode disposed on the second spline when the basketassembly is in the expanded state, and wherein the plurality of firstsplines and the second spline are self-supporting.
 36. Theelectrophysiology catheter of claim 35, wherein each of the plurality offirst splines comprises an electrode disposed thereon.
 37. Theelectrophysiology catheter of claim 35, wherein each of the plurality offirst splines and the second spline includes: a plurality of electrodesdisposed thereon; and, a plurality of conductors, each of the pluralityof conductors extending from a corresponding one of the plurality ofelectrodes to the proximal end of the basket electrode assembly.
 38. Theelectrophysiology catheter of claim 35, wherein the electrode on thesecond spline further comprises a plurality of electrodes.
 39. Theelectrophysiology catheter of claim 35, wherein the second splinecomprises one of a plurality of second splines.
 40. Theelectrophysiology catheter of claim 35, wherein at least one of theplurality of first splines and the second spline assumes a helical shapein the expanded state.